You wouldn't have to necessarily use hex either, but you would have to put some space between them then...
1-13-4-6-10-12...
Would work just as well.
And be somewhat less confusing for us dyscalculic folk. Somewhat. Seriously, I get the basics of what you're suggesting conceptually, but trying to execute a custom hex code made my eyes go cross for a moment there, haha.
I really would love some sort of facecode system put in if they're ever able. Also really handy if you want to replay a character, but can't just import them into a new game. For now, what I'll probably end up doing is taking screencaps of sliders and looks of the character from different angles to make sure I can recreate it as close as possible in future replays. It's what I used for my Hawkes and while not as fast as face codes or making a custom preset in the DA toolset for DA:O, it more or less worked out.
Hell, if I'm really lucky gibbed or someone else will do a DA:I save editor and be able to include a head morph import/export feature similar to ME 2/3